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1.
Lett Appl Microbiol ; 73(1): 64-72, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33825200

RESUMO

Potato viral disease has been a major problem in potato production worldwide including Russia. Here, we detected Potato Virus M (PVM), P (PVP), S (PVS), Y (PVY), and X (PVX) and Potato Leaf Roll Virus (PLRV) by RT-PCR on potato leaves and tubers from the Northwestern (NW), Volga (VF), and Far Eastern (FE) federal districts of Russia. Each sample was co-infected with up to five viruses. RT-PCR disclosed all six viruses in NW, three in VF, and five in FE. Phylogenetic analyses of PVM and PVS strains resolved all PVM isolates in Group O (ordinary) and all PVS isolates in Group O. Seven PVY strains were detected, and they included only recombinants. PVY recombinants were thus the dominant potato virus strains in Russia, although they widely varied among the regions. Our research provides insights into the geographical distribution and genetic variability of potato viruses in Russia.


Assuntos
Carlavirus/fisiologia , Luteoviridae/fisiologia , Doenças das Plantas/virologia , Vírus de Plantas/fisiologia , Solanum tuberosum/virologia , Filogenia , Folhas de Planta/virologia , Vírus de Plantas/genética , Federação Russa
2.
Gene ; 786: 145626, 2021 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-33798682

RESUMO

Viruses are abundant entities that infect almost every living organism. In recent years, Next Generation Sequencing coupled with bioinformatic analyses is widely adopted for identification of known and unknown viruses in a plant sample. In the present study, nine putative novel viruses were discovered from public domain transcriptome datasets of five endangered plant species by de novo assembly of reads using CLC and SPAdes followed by BLAST analysis. Of the identified viruses, ten coding-complete and five partial genomic segments were recovered. Based on phylogeny and BLAST analysis, the identified viruses were putatively assigned to various plant viral genera except dactylorhiza hatagirea benylike virus that probably represents a new group of plant virus. The methodology followed can be adopted for the discovery of novel viruses in plant species with little genomic information. Viral genome sequences recovered in the study will serve as a valuable resource for further characterization of identified viruses.


Assuntos
Perfilação da Expressão Gênica/métodos , Vírus de Plantas/classificação , Vírus de Plantas/isolamento & purificação , Plantas/genética , China , Biologia Computacional , Espécies em Perigo de Extinção , Sequenciamento de Nucleotídeos em Larga Escala , Índia , Filogenia , Vírus de Plantas/genética , Plantas/virologia , Análise de Sequência de RNA
3.
Arch Virol ; 166(6): 1711-1722, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33866416

RESUMO

Viruses are widespread in alfalfa (Medicago sativa L.), representing a key limitation to the production of this important forage plant. Understanding the diversity of plant viruses in alfalfa and their potential vectors will play an important role in management to minimize the emergence, transmission, and impact of viruses. Next-generation sequencing (NGS) targeting the transcriptome was applied to monitor the virus communities in alfalfa and its two main pests, thrips (Odontothrips loti Haliday and Frankliniella intonsa Trybom) and aphids (Acyrthosiphon pisum Mordvilko and Therioaphis trifolii Monell). A comparison of transcriptome datasets with reference databases revealed the presence of eight candidate viruses. Five out of the eight viruses, alfalfa mosaic virus (AMV), Medicago sativa alphapartitivirus 1 (MsAPV1), Medicago sativa deltapartitivirus 1 (MsDPV1), Medicago sativa amalgavirus 1 (MsAV1), and bean yellow mosaic virus (BYMV), were confirmed by RT-PCR. We identified and determined the presence of four RNA viruses from alfalfa samples, two viruses (AMV and MsAPV1) from thrips samples, and one virus (BYMV) from T. trifolii. All sequences isolated from the insect samples were more than 95% identical to the sequences from the alfalfa samples or to sequences from the National Center for Biotechnology Information (NCBI) reference database. The RNA-seq results of this study suggest that AMV and MsAPV1 are the predominant RNA plant viruses infecting alfalfa and that they are carried by the major pests. This lays the foundation for future research on the vectors and transmission of these viruses. In addition, the sequence data have enabled the assembly of the first complete genome sequence of MsDPV1 from alfalfa.


Assuntos
Afídeos/virologia , Medicago sativa/virologia , Vírus de Plantas/isolamento & purificação , RNA-Seq , Tisanópteros/virologia , Animais , China , Vírus de Plantas/classificação , Vírus de Plantas/genética , RNA Viral/genética
4.
Plant Physiol ; 185(2): 424-440, 2021 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-33721890

RESUMO

Orobanche cumana is a holoparasitic plant that attaches to host-plant roots and seriously reduces the yield of sunflower (Helianthus annuus L.). Effective control methods are lacking with only a few known sources of genetic resistance. In this study, a seed-soak agroinoculation (SSA) method was established, and recombinant tobacco rattle virus vectors were constructed to express RNA interference (RNAi) inducers to cause virus-induced gene silencing (VIGS) in sunflower. A host target gene HaTubulin was systemically silenced in both leaf and root tissues by the SSA-VIGS approach. Trans-species silencing of O. cumana genes were confirmed for 10 out of 11 target genes with silencing efficiency of 23.43%-92.67%. Knockdown of target OcQR1, OcCKX5, and OcWRI1 genes reduced the haustoria number, and silencing of OcEXPA6 caused further phenotypic abnormalities such as shorter tubercles and necrosis. Overexpression of OcEXPA6 caused retarded root growth in alfalfa (Medicago sativa). The results demonstrate that these genes play an important role in the processes of O. cumana parasitism. High-throughput small RNA (sRNA) sequencing and bioinformatics analyses unveiled the distinct features of target gene-derived siRNAs in O. cumana such as siRNA transitivity, strand polarity, hotspot region, and 21/22-nt siRNA predominance, the latter of which was confirmed by Northern blot experiments. The possible RNAi mechanism is also discussed by analyzing RNAi machinery genes in O. cumana. Taken together, we established an efficient host-induced gene silencing technology for both functional genetics studies and potential control of O. cumana. The ease and effectiveness of this strategy could potentially be useful for other species provided they are amenable to SSA.


Assuntos
Resistência à Doença/genética , Helianthus/genética , Orobanche/fisiologia , Doenças das Plantas/imunologia , Proteínas de Plantas/genética , Biologia Computacional , Expressão Gênica , Inativação Gênica , Helianthus/imunologia , Sequenciamento de Nucleotídeos em Larga Escala , Medicago sativa/genética , Medicago sativa/crescimento & desenvolvimento , Necrose , Orobanche/genética , Folhas de Planta/genética , Folhas de Planta/imunologia , Raízes de Plantas/genética , Raízes de Plantas/imunologia , Vírus de Plantas/genética , Interferência de RNA , Sementes/genética , Sementes/imunologia , Análise de Sequência de RNA , Tubulina (Proteína)/genética
5.
Arch Virol ; 166(6): 1575-1589, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33738562

RESUMO

This study examined the natural and experimental host range and aphid and graft transmission of the tentative polerovirus phasey bean mild yellows virus (PBMYV). Eleven complete coding sequences from PBMYV isolates were determined from a range of hosts and locations. We found two genetically distinct variants of PBMYV. PBMYV-1 was the originally described variant, and PBMYV-2 had a large putative recombination in open reading frame 5 such that PBMYV-1 and PBMYV-2 shared only 65-66% amino acid sequence identity in the P5 protein. The virus was transmitted by a clonal colony of cowpea aphids (Aphis craccivora) and by grafting with infected scions but was not transmitted by a clonal colony of green peach aphids (Myzus persicae). PBMYV was found in natural infections in 11 host species with a range of symptoms and severity, including seven important grain legume crops from across a wide geographic area in Australia. PBMYV was common and widespread in the tropical weed phasey bean (Macroptilium lathyroides), but it is likely that there are other major alternative hosts for the virus in temperate regions of Australia. The experimental host range of PBMYV included the Fabaceae hosts chickpea (Cicer arietinum), faba bean (Vicia faba), pea (Pisum sativum), and phasey bean, but transmissions failed to infect several other members of the families Asteraceae, Cucurbitaceae, Fabaceae and Solanaceae. PBMYV was commonly found in grain legume crops in eastern and western Australia, sometimes at greater than 90% incidence. This new knowledge about PBMYV warrants further assessments of its economic impact on important grain legume crops.


Assuntos
Fabaceae/virologia , Variação Genética , Vírus de Plantas/genética , Vírus de Plantas/fisiologia , Animais , Afídeos/virologia , Austrália , Filogenia , Doenças das Plantas/virologia
6.
Arch Virol ; 166(6): 1763-1767, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33755801

RESUMO

Rice (Oryza sativa L.) is an important food crop for humanity, being cultivated in tropical and temperate regions of the world. This study reports the nearly complete genome sequences of four Brazilian rice stripe necrosis virus (RSNV) isolates. The nucleotide sequences of the RNA1 and RNA2 genome segments of these Brazilian isolates were 96.5 to 99.9% identical, indicating their close phylogenetic relationship to each other. Phylogeny and recombination analysis indicated that the genome of one of the isolates consisted of RNA segments of different origins, suggesting that a reassortment event had occurred.


Assuntos
Oryza/virologia , Vírus de Plantas/genética , Brasil , Filogenia
7.
Arch Virol ; 166(6): 1775-1778, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33772366

RESUMO

In the present work, we report the discovery and complete genome sequence of a novel partitivirus identified from Brassica campestris L. ssp. chinensis, which we have named "Brassica campestris chinensis cryptic virus 1" (BCCV1). Next-generation sequencing (NGS) combined with adapter-ligation-mediated amplification allowed assembly of the full-length genome sequence of BCCV1. The genome of BCCV1 contains two dsRNA segments, dsRNA1 (1595 bp) and dsRNA2 (1591 bp), which encode a conserved RNA-dependent RNA polymerase (RdRp) and a putative capsid protein (CP), respectively. Homology searches and phylogenetic analysis of the 479-aa RdRp and 438-aa CP showed that BCCV1 is a new member of the genus Deltapartitivirus, family Partitiviridae. This is the first report of the identification of a member of the family Partitiviridae in Brassica campestris L. ssp. chinensis.


Assuntos
Brassica/virologia , Doenças das Plantas/virologia , Vírus de Plantas/genética , RNA/genética , Sequência de Bases , Filogenia
8.
Virologie (Montrouge) ; 25(1): 29-42, 2021 Feb 01.
Artigo em Francês | MEDLINE | ID: mdl-33650495

RESUMO

Plant virus ecology began to be explored at the end of the 19th century. Since then, major advances have revealed complex virus-host-vector interactions in a variety of environments. These advances have been accelerated by development of new technologies for virus detection and characterization, the latest of which being high-throughput sequencing (HTS). HTS technologies have proved to be effective for non-targeted characterization of all or nearly all viruses present in a sample without requiring prior information about virus identity, as would be needed for virus-targeted tests. Phytoviromic studies have thus made important advances, including characterization of the complex interactions between phytovirus dynamics and the structure of multi-species host communities, and documentation of the effects of anthropogenic ecosystem simplification on plant virus emergence and diversity. However, such studies must overcome challenges at every stage, from plant sampling to bioinformatics analysis. This review summarizes major advances in plant virus ecology, in association with technological developments, and presents key considerations for use of HTS in the study of the ecology of phytovirus communities.


Assuntos
Ecossistema , Vírus de Plantas , Vírus de DNA , Ecologia , Nucleotídeos , Vírus de Plantas/genética
9.
Proc Natl Acad Sci U S A ; 118(6)2021 02 09.
Artigo em Inglês | MEDLINE | ID: mdl-33526695

RESUMO

Environmental conditions are an important factor driving pathogens' evolution. Here, we explore the effects of drought stress in plant virus evolution. We evolved turnip mosaic potyvirus in well-watered and drought conditions in Arabidopsis thaliana accessions that differ in their response to virus infection. Virus adaptation occurred in all accessions independently of watering status. Drought-evolved viruses conferred a significantly higher drought tolerance to infected plants. By contrast, nonsignificant increases in tolerance were observed in plants infected with viruses evolved under standard watering. The magnitude of this effect was dependent on the plant accessions. Differences in tolerance were correlated to alterations in the expression of host genes, some involved in regulation of the circadian clock, as well as in deep changes in the balance of phytohormones regulating defense and growth signaling pathways. Our results show that viruses can promote host survival in situations of abiotic stress, with the magnitude of such benefit being a selectable trait.


Assuntos
Arabidopsis/genética , Interações Hospedeiro-Patógeno/genética , Doenças das Plantas/genética , Vírus de Plantas/genética , Simbiose/genética , Adaptação Fisiológica , Arabidopsis/virologia , Brassica napus/genética , Brassica napus/virologia , Secas , Evolução Molecular , Regulação da Expressão Gênica de Plantas/genética , Doenças das Plantas/virologia , Reguladores de Crescimento de Plantas/genética , Vírus de Plantas/patogenicidade , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/virologia , Potyvirus/genética , Potyvirus/patogenicidade , Estresse Fisiológico/genética
10.
Nucleic Acids Res ; 49(4): 1900-1913, 2021 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-33524108

RESUMO

Short non-coding RNA molecules (sRNAs) play a fundamental role in gene regulation and development in higher organisms. They act as molecular postcodes and guide AGO proteins to target nucleic acids. In plants, sRNA-targeted mRNAs are degraded, reducing gene expression. In contrast, sRNA-targeted DNA sequences undergo cytosine methylation referred to as RNA-directed DNA methylation (RdDM). Cytosine methylation can suppress transcription, thus sRNAs are potent regulators of gene expression. sRNA-mediated RdDM is involved in genome stability through transposon silencing, mobile signalling for epigenetic gene control and hybrid vigour. Since cytosine methylation can be passed on to subsequent generations, RdDM contributes to transgenerational inheritance of the epigenome. Using a novel approach, which can differentiate between primary (inducer) and secondary (amplified) sRNAs, we show that initiation of heritable RdDM does not require complete sequence complementarity between the sRNAs and their nuclear target sequences. sRNAs with up to four regularly interspaced mismatches are potent inducers of RdDM, however, the number and disruptive nature of nucleotide polymorphisms negatively correlate with their efficacy. Our findings contribute to understanding how sRNA can directly shape the epigenome and may be used in designing the next generation of RNA silencing constructs.


Assuntos
Interferência de RNA , Pequeno RNA não Traduzido/química , Metilação de DNA , Genes Homeobox , Vírus de Plantas/genética , Plantas Geneticamente Modificadas , Tabaco/genética
11.
Nat Commun ; 12(1): 1007, 2021 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-33579946

RESUMO

Plant viruses cause massive crop yield loss worldwide. Most plant viruses are RNA viruses, many of which contain a functional tRNA-like structure. RNase P has the enzymatic activity to catalyze the 5' maturation of precursor tRNAs. It is also able to cleave tRNA-like structures. However, RNase P enzymes only accumulate in the nucleus, mitochondria, and chloroplasts rather than cytosol where virus replication takes place. Here, we report a biotechnology strategy based on the re-localization of plant protein-only RNase P to the cytosol (CytoRP) to target plant viruses tRNA-like structures and thus hamper virus replication. We demonstrate the cytosol localization of protein-only RNase P in Arabidopsis protoplasts. In addition, we provide in vitro evidences for CytoRP to cleave turnip yellow mosaic virus and oilseed rape mosaic virus. However, we observe varied in vivo results. The possible reasons have been discussed. Overall, the results provided here show the potential of using CytoRP for combating some plant viral diseases.


Assuntos
Resistência à Doença/fisiologia , Ribonuclease P/genética , Ribonuclease P/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Cloroplastos/metabolismo , Vírus do Mosaico/genética , Vírus do Mosaico/metabolismo , Vírus de Plantas/genética , Protoplastos/metabolismo , Precursores de RNA/metabolismo , RNA de Transferência/genética , Ribonuclease P/química
12.
Arch Virol ; 166(3): 987-990, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33462672

RESUMO

We report the complete nucleotide sequence of the genome of a novel virus in ringspot-diseased common oak (Quercus robur L.). The newly identified pathogen is associated with leaf symptoms such as mottle, chlorotic spots and ringspots on diseased trees. High-throughput sequencing (HTS, Illumina RNASeq) was used to explore the virome of a ringspot-diseased oak that had chlorotic ringspots of suspected viral origin on leaves for several years. Bioinformatic analysis of the HTS dataset followed by RT-PCR enabled us to determine complete sequences of four RNA genome segments of a novel virus. These sequences showed high similarity to members of the genus Emaravirus, which includes segmented negative-stranded RNA viruses of economic importance. To verify the ends of each RNA, we conducted rapid amplification of cDNA ends (RACE). We identified an additional genome segment (RNA 5) by RT-PCR using a genus-specific primer (PDAP213) to the conserved 3´ and 5´termini in order to amplify full-length genome segments. RNA 5 encodes a 21-kDa protein that is homologous to the silencing suppressor P8 of High Plains wheat mosaic virus. The five viral RNAs were consistently detected by RT-PCR in ringspot-diseased oaks in Germany, Sweden, and Norway. We conclude that the virus represents a new member of the genus Emaravirus affecting oaks in Germany and in Scandinavia, and we propose the name "common oak ringspot-associated emaravirus" (CORaV).


Assuntos
Bunyaviridae/classificação , Bunyaviridae/genética , Genoma Viral/genética , Vírus de Plantas/genética , Quercus/virologia , Sequência de Aminoácidos , Sequência de Bases , Bunyaviridae/isolamento & purificação , Alemanha , Sequenciamento de Nucleotídeos em Larga Escala , Noruega , Filogenia , Doenças das Plantas/virologia , Folhas de Planta/virologia , Vírus de Plantas/classificação , RNA Viral/genética , Alinhamento de Sequência , Suécia
13.
Viruses ; 13(1)2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33401517

RESUMO

We are pleased to present in this Special Issue a series of reviews and research studies on the topic of "Plant Virus Emergence" [...].


Assuntos
Vírus de Plantas/isolamento & purificação , Plantas/virologia , Doenças das Plantas/virologia , Vírus de Plantas/genética
14.
Curr Opin Plant Biol ; 60: 101992, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33450609

RESUMO

Plant viruses have been engineered to express heterologous proteins and RNAs in plants for several decades. This viral system can now be applied to editing plant genomes. Virus vectors can deliver Cas proteins and guide RNAs, two key components of the CRISPR gene-editing system, into a plant cell without a complicated experimental procedure. In some cases, plant viruses move to meristematic cells and express gene-editing components in the cell, which results in the production of mutant seeds. Here, we focus on three main issues of the virus-induced genome editing (VIGE) technology in plants: (1) how to express the relatively large size of Cas proteins, (2) how to express guide RNA, and (3) how to increase the efficiency with which viruses are delivered into meristematic cells. We highlight recent advances in how plant virus vectors can be used efficiently in plant-genome editing.


Assuntos
Edição de Genes , Vírus de Plantas , Sistemas CRISPR-Cas/genética , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Genoma de Planta , Vírus de Plantas/genética , RNA Guia
15.
Plant Dis ; 105(4): 948-957, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32915119

RESUMO

In this study, a set of duplex reverse transcription PCR (RT-PCR)-mediated high-resolution DNA melting (HRM) analyses for simultaneous detection of potato mop-virus (PMTV) and its protist vector, Spongospora subterranea f. sp. subterranea (Sss), was developed. The infestation of soil by PMTV was detected with a tobacco-based baiting system. Total RNA extracted from the soil led to successful RT-PCR gel electrophoresis detection of both PMTV and Sss. To facilitate more efficient detection, newly designed primer pairs for PMTV RNA species (i.e., RNA-Rep, RNA-CP, and RNA-TGB) were analyzed together with the existing Sss primers via real-time RT-PCR. The resulting amplicons exhibited melting profiles that could be readily differentiated. Under duplex RT-PCR format, all PMTV and Sss primer combinations led to successful detection of respective PMTV RNA species and Sss in the samples by HRM analyses. When the duplex HRM assay was applied to soil samples collected from six fields at four different sites in New Brunswick, Canada, positive detection of PMTV or Sss was found in 63 to 100% samples collected from fields in which PMTV-infected tubers had been observed. In contrast, the samples from fields where neither PMTV- nor Sss-infected tubers had been observed resulted in negative detection by the assay. Bait tobacco bioassay for PMTV and Sss produced similar results. Of the soil samples collected from PMTV-infested fields, 63 to 83% and 100% led to PMTV and Sss infections in the bait tobacco plants, respectively, whereas no PMTV- or Sss-infected plants were obtained from soil samples collected from PMTV- and Sss-free fields.


Assuntos
Vírus de Plantas , Canadá , Desnaturação de Ácido Nucleico , Doenças das Plantas , Vírus de Plantas/genética , Solo
16.
RNA ; 27(1): 27-39, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33008837

RESUMO

Viruses commonly use specifically folded RNA elements that interact with both host and viral proteins to perform functions important for diverse viral processes. Examples are found at the 3' termini of certain positive-sense ssRNA virus genomes where they partially mimic tRNAs, including being aminoacylated by host cell enzymes. Valine-accepting tRNA-like structures (TLSVal) are an example that share some clear homology with canonical tRNAs but have several important structural differences. Although many examples of TLSVal have been identified, we lacked a full understanding of their structural diversity and phylogenetic distribution. To address this, we undertook an in-depth bioinformatic and biochemical investigation of these RNAs, guided by recent high-resolution structures of a TLSVal We cataloged many new examples in plant-infecting viruses but also in unrelated insect-specific viruses. Using biochemical and structural approaches, we verified the secondary structure of representative TLSVal substrates and tested their ability to be valylated, confirming previous observations of structural heterogeneity within this class. In a few cases, large stem-loop structures are inserted within variable regions located in an area of the TLS distal to known host cell factor binding sites. In addition, we identified one virus whose TLS has switched its anticodon away from valine, causing a loss of valylation activity; the implications of this remain unclear. These results refine our understanding of the structural and functional mechanistic details of tRNA mimicry and how this may be used in viral infection.


Assuntos
Variação Genética , Vírus de Insetos/genética , Filogenia , Vírus de Plantas/genética , RNA de Transferência de Valina/química , RNA Viral/química , Anticódon/química , Anticódon/metabolismo , Sequência de Bases , Sítios de Ligação , Biologia Computacional , Vírus de Insetos/classificação , Vírus de Insetos/metabolismo , Modelos Moleculares , Mimetismo Molecular , Vírus de Plantas/classificação , Vírus de Plantas/metabolismo , Dobramento de RNA , RNA de Transferência de Valina/genética , RNA de Transferência de Valina/metabolismo , RNA Viral/genética , RNA Viral/metabolismo , Homologia de Sequência do Ácido Nucleico , Valina/metabolismo
17.
Phytopathology ; 111(1): 227-236, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32648524

RESUMO

Seven isolates of a putative cytorhabdovirus (family Rhabdoviridae, order Mononegavirales) designated as citrus-associated rhabdovirus (CiaRV) were identified in citrus, passion fruit, and paper bush from the same geographical area in China. CiaRV, bean-associated cytorhabdovirus (Brazil), and papaya virus E (Ecuador) should be taxonomically classified in the species Papaya cytorhabdovirus. Due to natural mutations, the glycoprotein (G) and P4 genes were impaired in citrus-infecting isolates of CiaRV, resulting in an atypical rhabdovirus genome organization of 3' leader-N-P-P3-M-L-5' trailer. The P3 protein of CiaRV shared a common origin with begomoviral movement proteins (family Geminiviridae). Secondary structure analysis and trans-complementation of movement-deficient tomato mosaic virus and potato virus X mutants by CiaRV P3 supported its function in viral cell-to-cell trafficking. The wide geographical dispersal of CiaRV and related viruses suggests an efficient transmission mechanism, as well as an underlying risk to global agriculture. Both the natural phenomenon and experimental analyses demonstrated presence of the "degraded" type of CiaRV in citrus, in parallel to "undegraded" types in other host plant species. This case study shows a plant virus losing the function of an important but nonessential gene, likely due to host shift and adaption, which deepened our understanding of course of natural viral diversification.


Assuntos
Vírus de Plantas , Rhabdoviridae , Brasil , China , Equador , Genoma Viral , Glicoproteínas , Fases de Leitura Aberta , Filogenia , Doenças das Plantas , Vírus de Plantas/genética , Rhabdoviridae/genética
18.
Phytopathology ; 111(1): 32-39, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33210987

RESUMO

The genomics era has revolutionized studies of adaptive evolution by monitoring large numbers of loci throughout the genomes of many individuals. Ideally, the investigation of emergence in plant viruses requires examining the population dynamics of both virus and host, their interactions with each other, with other organisms and the abiotic environment. Genetic mechanisms that affect demographic processes are now being studied with high-throughput technologies, traditional genetics methods, and new computational tools for big-data. In this review, we discuss the utility of these approaches to monitor and detect changes in virus populations within cells and individuals, and over wider areas across species and communities of ecosystems. The advent of genomics in virology has fostered a multidisciplinary approach to tackling disease risk. The ability to make sense of the information now generated in this integrated setting is by far the most substantial obstacle to the ultimate goal of plant virology to minimize the threats to food security posed by disease. To achieve this goal, it is imperative to understand and forecast how populations respond to future changes in complex natural systems.


Assuntos
Metagenômica , Vírus de Plantas , Ecologia , Ecossistema , Doenças das Plantas , Vírus de Plantas/genética
19.
New Phytol ; 229(3): 1650-1664, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-32945560

RESUMO

Viral infections are accompanied by a massive production of small interfering RNAs (siRNAs) of plant origin, such as virus-activated (va)siRNAs, which drive the widespread silencing of host gene expression, and whose effects in plant pathogen interactions remain unknown. By combining phenotyping and molecular analyses, we characterized vasiRNAs that are associated with typical mosaic symptoms of cauliflower mosaic virus infection in two crops, turnip (Brassica rapa) and oilseed rape (Brassica napus), and the reference plant Arabidopsis thaliana. We identified 15 loci in the three infected plant species, whose transcripts originate vasiRNAs. These loci appear to be generally affected by virus infections in Brassicaceae and encode factors that are centrally involved in photosynthesis and stress response, such as Rubisco activase (RCA), senescence-associated protein, heat shock protein HSP70, light harvesting complex, and membrane-related protein CP5. During infection, the expression of these factors is significantly downregulated, suggesting that their silencing is a central component of the plant's response to virus infections. Further findings indicate an important role for 22 nt long vasiRNAs in the plant's endogenous RNA silencing response. Our study considerably enhances knowledge about the new class of vasiRNAs that are triggered in virus-infected plants and will help to advance strategies for the engineering of gene clusters involved in the development of crop diseases.


Assuntos
Arabidopsis , Vírus de Plantas , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Fotossíntese , Doenças das Plantas/genética , Vírus de Plantas/genética , RNA Interferente Pequeno
20.
Biochemistry ; 59(49): 4663-4680, 2020 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-33269926

RESUMO

The plant Sesbania mosaic virus [a (+)-ssRNA sobemovirus] VPg protein is intrinsically disordered in solution. For the virus life cycle, the VPg protein is essential for replication and for polyprotein processing that is carried out by a virus-encoded protease. The nuclear magnetic resonance (NMR)-derived tertiary structure of the protease-bound VPg shows it to have a novel tertiary structure with an α-ß-ß-ß topology. The quaternary structure of the high-affinity protease-VPg complex (≈27 kDa) has been determined using HADDOCK protocols with NMR (residual dipolar coupling, dihedral angle, and nuclear Overhauser enhancement) restraints and mutagenesis data as inputs. The geometry of the complex is in excellent agreement with long-range orientational restraints such as residual dipolar couplings and ring-current shifts. A "vein" of aromatic residues on the protease surface is pivotal for the folding of VPg via intermolecular edge-to-face π···π stacking between Trp271 and Trp368 of the protease and VPg, respectively, and for the CH···π interactions between Leu361 of VPg and Trp271 of the protease. The structure of the protease-VPg complex provides a molecular framework for predicting sites of important posttranslational modifications such as RNA linkage and phosphorylation and a better understanding of the coupled folding upon binding of intrinsically disordered proteins. The structural data presented here augment the limited structural data available on viral proteins, given their propensity for structural disorder.


Assuntos
Proteínas Intrinsicamente Desordenadas/química , Vírus de Plantas/química , Proteínas Virais/química , Sequência de Aminoácidos , Aminoácidos Aromáticos/química , Fenômenos Biofísicos , Interações Hidrofóbicas e Hidrofílicas , Proteínas Intrinsicamente Desordenadas/genética , Modelos Moleculares , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Ressonância Magnética Nuclear Biomolecular , Vírus de Plantas/genética , Ligação Proteica , Conformação Proteica , Dobramento de Proteína , Mapeamento de Interação de Proteínas , Eletricidade Estática , Proteínas Virais/genética
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